Sabot projectile



4Filed July 2l, 196e Oce. si, 1967 Q, SCHWAGER Em.. 3,349,712

SABOT PRQJEGTILE 2 Sheets-Sheet l f1 0t.31,1967 -f R 3,34312 SABOTPROJECTILE Filed July 2l, 1966 2 Shee's-Shea' 2 162/ 14ga Fly.

United States Patent Oil ABSTRACT OF THE DISCLOSURE A sabot projectilewherein the sabot is connected to the projectile body by a connectingpiece which can be sheared due to the inertia of the projectile whenfired. This is provided by shearing edges located upon the sabot and theprojectile rear surface.

The invention relates to a sabot projectile of the kind in which a sabotis connected to a base surface of a projectile -body by means of aconnecting piece projecting over the base surface, which connectingpiece, on discharge, owing to the load due to the inertia of theprojectile body, is sheared off and causes severance of the connection.

In a sabot projectile of thi-s kind disclosed in United States PatentNo. 3,044,400 granted July 17, 1962 the connecting parts are constructedas threaded bolts with bonding connections which engage in holes whichare formed inthe projectile body parallel to the projectile axis. Such aprojectile is difficult to produce and therefore also expensive,especially in the case of projectiles of hard metal such, for example,as tungsten carbide. A further disadvantage of such a projectile is thatthe holes Serving for the engagement of the bolts can be the cause ofcracks which occur when the bolts which, acting on the projectile bodyon feeding the sabot projectile into the chamber of the barrel of anautomatic weapon, transmit forwardly directed inertia force to thesabot. As a result of such cracks arising on feeding, on the suddenacceleration of the projectile body and severance of the bolts ondischarge, parts of the projectile body can alre olf, cause an imbalanceof the same and thus a reduction in accuracy of its flight. In the caseof securing the projectile body for transport or loading through boltsof this kind provided at its rear part, such cracks radiating from theholes can, moreover, on impact of the projectile body, for example, -onan armour plate representing the target, produce a weakening of theprojectile body which considerably alfects its penetrating power. With asabot projectile of the above kind, the danger also exists that theconnecting parts can break prematurely if a hard impact occurs in thechamber on loading. Here the determining factor is the shearingresistance of the adhesive bond. It is diicult to determine thisresistance correctly between 'given edges on relatively small surfaces.

The invention overcomes the abovesaid disadvantages in that it providesa sabot projectile consisting of a projectile body having a base surfaceat one end, a discshaped connecting piece secured to the base surface bymeans of a bonding substance and constituting a rim extendingcircumferentially beyond the base surface, a sabot having the form of asleeve in which the projectile body is received and which is closedatits rear end by a Wall portion, a ring surface forming an innersurface part of the end wall portion and dening a circular recess in thesaid end wall, the said ring surface co-axially seating against the rimof the connecting piece and further defining a circular shearing edgearound the periphery of the recess which edge shears through theconnecting piece 3,349,712 Patented Oct. 3l, 1967 ICC projectile isdischarged due to the inprojectile body causing the said body to enterwhen the sabot ertia of the the recess.

In accordance with the invention, owing to securing the disc-shapedconnecting part to the base surface of the projectile body by adhesion,the occurrence of cracks in the latter and thereby the impairment of itsefliciency, is avoided. Owing to the fact that holes and screw threadsin the projectile body are avoided and thus no costly machining isnecessary for the projectile body consisting either of hard metal orhigh-alloy steel, there results the cheapening of manufacture andimprovement of the sabot projectile which are sought. When measuring theresistance of the severance the determining factor is no longer theadhesive bond, but the precisely dimensionable rim of the connectingpiece.

Five preferred embodiments of the invention will hereinafter bedescribed, by way of example, with reference to the accompanyingdrawings in which:

FIGURE 1 shows a first embodiment of a sabot projectile in longitudinalsection and partial elevation,

FIGURES 2 and 2a show a greatly enlarged broken longitudinal section ofthe rear part of the Sabot projectile shown in FIGURE l, with sectionpart A in FIG. 2 showing the sabot projectile in the condition prior toloading, and section part B in FIG. 2a showing the sabot projectileafter discharge on passing through a gun barrel (not shown),

FIGURES 3 and 3a are a representation corresponding to FIGURES 2 and 2aof a second embodiment,

FIGURES 4 and 4a1 are a representation corresponding to FIGURES 2 and2a, of a third embodiment,

FIGURES 5 and 5a are a representation corresponding to FIGURES 2 and 2a,of a fourth embodiment, and

FIGUR-ES 6` and 6a are a representation corresponding to FIGURES 2 and2a of a lifth embodiment.

In FIGURE l, the sabot is marked 10 and the projectile body 11. Thesleeve-shaped sabot 10, of light metal such as aluminium alloy, ts withits rear part into the mouth of a cartridge case (not shown), in a knownmanner, until discharge. The projectile body 11, preferably wholly or inpart consisting of tungsten carbide, is cylindrical in shape and issupplemented by a leading point 21 and a short projectile body boat-tail110, which is in the form of a truncated circular cone. The steeldriving band 12 is secured to the sabot`10 and transmits to it thespinning impulse from the grooves in the gun barrel (not shown). Anothersimilar driving band 13 is arranged at the front part of the sabot 10.In order to save weight, the outside diameter of the sabot 10 lyingbetween the two driving bands 12 and 13 is of smaller diameter than thebase portion.

The front cylindrical hole 101 in the sabot 10 serves to centre andguide the projectile body 11. This hole 101 opens out, forming ashoulder 103, into a coaxial hole 102 of larger diameter, formed in thebase of the sabot 10, the rear portion of which carries a screw thread.A screw-in body 15, with a recess 16 in it, is fitted into this screwedportion of the sabot 10 from the rear. Between this shoulder 103 and thescrew-in body 15 there is clamped the disc-shaped connecting piece 14,which is secured to the projectile base surface 111.

FIGURES 2 and 2a show, in a first embodiment of the invention, thedetails of securing the projectile body 11 to the sabot 10. Adisc-shaped connecting piece 14a, made of brass `or steel for example,is securely connected by hard soldering, by means of a layer of hardsolder 24, to the truncated circular cone which forms the boattail ofprojectile body 11, or to its end face presenting the base surface 111.The part of the disc 14a, hereafter called the shearing rim 141,projecting beyond the diameter of the base surface 111 and theprojectile body 11, bears against the ring-shaped front surface 151 ofthe screw-in body Iand is pressed by the latter against the shoulder 103of the sabot 10 formed by the joint between the two holes 101 and 102.From the front surface 151 of the screw-in body 15, extending to therear, a recess 16a is formed, bounding a truncated cone-shaped space,contracting towards the rear, the base 16-1a of which is arrangedparallel to the rear end surface 143a of the disc 14a, therefore atright angles to the projectile axis. The line of intersection of thefront surface 151 with the generated surface 16211 of the recess 16aforms an edge which will hereafter be called the shearing edge 152.. Itsdiameter is at least as great as the diameter of the base surface 111 ofthe projectile body 11.

The generatrices of the truncated cone of the projectile body boat-tail110 and the generated surface 162a of the recess 16a essentially form anangle of the same size with the longitudinal axis of the projectile. Itmust, however, be greater than the angle at which jamming in regard toseparation of the two cones in the axial direction occurs throughfriction.

The height of the projectile body boat-tail 110 is, moreover, at leastequal to the thickness of the shearing rim 141 of the disc 14a. In thecase of this version (FIG- URES 2 and 2a) the height is for example, 1.4times this thickess.

The distance of the base 161a of the recess 16a from the rear endsurface 143a of the disc 14a, which in this example is the same as thedepth of the recess 16a, is so dimensioned that it is at least equal tothe thickness of the shearing -rim 141, but at most equal to the heightof the cone-shaped projectile body boat-tail 110. In the case of theabove version, it is equal to half the surn of the height of thisprojectile 4body boat-tail 110 and the thickness of the shearing rim141.

In the case of the subsequently described embodiments shown in FIGURES 3and 3a to 6 and 6a, corresponding parts are similarly numbered; partsaltering in shape are supplemented with the lletters a to e in suchfigures and, in addition, new accessory components receive a new number.

The second and third embodiments of a sabot projectile illustrated inFIGURES 3 and 3a and 4 and 4a differ from the previously describedembodiment as shown in FIGURES 2 and 2a, in that the disc-shapedconnecting piece secured to the projectile body boattail 110 is formedby the disc 14a, containing the shearing rim 141 and, superimposedcoaxially on its rear side, a truncated cone 152a or 142b, tapering tothe rear, combined into one body with the disc 14a. The base surface ofthe truncated cone 142er has a diameter which, in the case of the sabotprojectile shown in FIGURES 3 and 3a, is the same size as, and with thetruncated cone 142b shown in FIGURES 4 and 4a is smaller than, thediameter of the shearing edge 152 of the screw-in -body 15.

The depth of the recess 16b is here determined, following the example ofthe rst embodiment in FIGURES 2 and 2a, by the requirement that thedistance of its base 151b from the rear end surface 143b of thetruncated cone 142a or 1,4211 is at least equal to the thickness of theshearing rim 141, but at most equal to the height of the conedprojectile body boat-tail 110. In the two embodiments shown in FIGURES 3and 3a and 4 and 4a this distance is equa-l to half the sum of theprojectile body boattail 110 and the thickness of the shearing rim 141.

The angles of inclination of the generatrices of the truncated cone14211 or 142b and the .recess 16b in relation to the base surface 111 ofthe projectile body are the same size.

Unlike the version as in FIGURES 2 and 2a, in which the front face ofthe shearing rim 141 lies in the same plane as the projectile basesurface 111, in FIGURES 5 and 5a a truncated cone 147, widening to thefront, is mounted on the front face of the disc-shaped connecting pieceon the disc 14a containing the shearing rim 141, forming one piece withthe disc 14a. The front end surface of this truncated cone is, as in theforegoing embodiments, secured to the projectile base surface 111 by ahard solder layer 24. The rear end surface of this truncated cone 147forms the transition surface to the disc 14a and has a diameter which isat most equal to the diameter of the shea-ring edge 152..

The height of this truncated cone 147 is at least equal to the thicknessof the shearing rim 141 and its cone angle is essentially the same asthat of the recess 16C in the screw-in body 15. The distance of the base161e of the recess 16e from the rear end surface 143a of the disc 14a isat least equal to the thickness of the shearing rim 141, but at mostequal to the height of the truncated cone 147. In the embodiment shownin FIGURES 5 and 5a, it is equal to -half the sum of the thickness ofthe shearing rim 141 and the height of the truncated cone 147.

The fifth embodiment of a sabot projectile shown in FIGURES 6 and 6adiffers from the embodiments shown in FIGURES 3 and 3a and 4 and 4adescribed above in one way; that is, the recess 1617 forms the frontportion of a hole 17, 18 completely and centrally piercing the screw-inbody 15, which opens out into the base opening 104 of the sabot 10. Themiddle portion 17 of this hole is cylindrical, whilst its rear portion18 widens out in a cone shape in the direction of the base opening 104.Another difference is that the disc-shaped connecting piece 14a, 142Cbonded to the projectile body boat-tail is the carrier of a casing 19arranged in the middle portion 17 of the hole and reaching through toits rear portion 18, which contains, for example, a tracer composition20. On account of these through holes 17, 18 during shot travel in thebore of the gun, the propellant gases do not only impinge on the basesurface of the sabot 10, but also on the base surface of the projectilebody 11. The relative magnitudes of these surfaces and the weights ofsabot 10 and |projectile body 11 are such that the acceleration to whichthe sabot projectile shaped as in FIGURES 6 and 6a is subjected duringthis movement is considerably greater than that imparted to theprojectile body 11 by the gas force. The inertia of the projectile body11 is therefore preponderant and, as in the previous embodiments, causesthe shearing through of the connecting piece.

The material of that part of the screw-in body 15 of the tiveembodiments of the invention described, in which the recesses 16 arelformed, has a higher strength than the material from which theconnecting pieces 14 secured to the projectile body boat-tail 110 aremade.

The mode of operation of the sabot projectiles will hereinafter bedescribed, immediately before discharge, during the loading process, andduring the discharge itself.

If a cartridge, of which the sabot projectile forms a part up todischarge is suddenly checked at the end of the feeding process onloading into the chamber of an automatic gun, as a result of its forwardinertial force the projectile body 11 is supported, by means of theconnecting piece 14 secured to it, through the shearing rim 141, on theshoulder 103 of the sabot 10 (see FIGURE 1). In this connection, theshearing rim 141 is so dimensioned that it withstands this load causedby the inertial force, and thus no premature separation of theprojectile body 11 from the sabot 10 can take place as a result ofbreakage of the connecting piece 14.

After the ignition of the propellant charge, however,

as a result of the enormous acceleration of the sabot projectile in thebarrel of the gun, such a great inertial force acts on the projectilebody 11 that, acting as a shearing punch to the' rear in relation to thesabot 10, and in conjunction with the shearing edge 152 and the frontsurface 151 of the screw-in body 15, which represents a counterholdingshearing ring, it shears through the shearing rim 141 along thecircumference of the projectile base surface 111 (see, 2a).

At the end of this shear movement, the projectile body 11, together withthe sheared-olf component 145a, 145b, 145e, 145d or 145e, supportsitself to the rear, that is, according to the design version in eachcase of one of the ve examples, either (FIGURE 6a) through theintersecting plane 146e of the (thereby strongly compressed) component145e against the generated surface 162b of the recess 16h, or (FIGURE4a) through the rear end surface 143b of the component 145C (thereforewithout the compression of the previous example) against the base 161bof the recess 16b then acting as an abutment, or on the other hand(FIGURES 2a, 3a) through the component 145a or 145b, against these twosupporting surfaces at the same time.

In each of the embodiments, the projectile body 11 is caused to rotateby the friction which acts between it and these supporting surfacestransmitting the spin of the screw-in body 15 or the sabot 10.

In the case of the embodiment shown in FIGURES 6 and 6a, which isidentical with the embodiment according to FIGURES 3 and 3a as regardsthe supporting of the projectile body 11 on the tapered recess Wall 162bafter discharge, the rearward movement of the projectile body 11 inrelation to the sabot 10 on discharge comes to rest when the sum of theaxial component of the reaction force transmitted by the recess wall162b and the gas Iforce acting on it through the casing 19 is of thesame magnitude as the inertia force acting on it. The conditions can beso adjusted, as with the version under consideration, that this is thecase when the relative distance covered by the projectile body is equalto half the sum of the height of the tapered projectile body boat-tail110 and the thickness of the shearing rim 141. The tracer composition 20which may, for example, be contained in the casing 19, is ignited by thehot propellant gases during the passage of the sabot projectile down thegun barrel.

During the rearward movement of the projectile body 11 moreover, thesheared-oif ring-shaped shearing rim 141, gripped between the shoulder103 of the sabot 10 and the ring-shaped frame surface 151 of thescrew-in body 15, is also compressed on the surface of cut 144,corresponding to the shape of the tapered boat-tail 110 of theprojectile body 11 (see, for example, FIGURE 2a). Similarly, thesheared-olf component 14511, 145b, 145e, 145d or 145e, hard soldered tothe projectile body boattail 110, situated in a shearing position onpenetrating into the recess 16a, 16b or 16C of the screw-in body 15, isalso deformed into a truncated cone by compression on the intersectingplane 14611, 146b, 146C, 146d or 146e.

As a result of the selection of the height of the tapered for example,FIGURE projectile boat-tail 110, together with the thickness of v theshearing rim 141 on the one hand, and the clearance existing in thecondition before loading of the recess base 161a, 161b or 161C from therear end surface 143a or 143b of the connecting part on the other hand,the relative displacement path of the projectile body 11 in the sabot 10is so dimensioned that the rear inside diameter of the surface of cut144 of the shearing rim 141 is a little larger than the front outsidediameter of the sheared-oif component 145a, 145b, 145C, 145d or 145esecured to the projectile base surface 111 of the projectile body 11. Bythis means, and furthermore owing to the smoothing of the surface of cut144 and the intersecting plane 146:1, 146b, 146e, 146d or 146e, thedanger is eliminated with certainty that burns, or the like, arisenthrough dirty surfaces on the shearing rim 141 and/ or on the cut-olfcomponent 145a, 145b, 145C, 145d or 145e, acting as resistances shouldcheck, or even completely prevent, separation movement of the projectilebody 11 in relation to the sabot 10 to be carried out by the sabotprojectile after leaving the gun barrel.

The forward inertia force acting on the projectile body 11 at the end offeeding in a cartridge into a chamber URES 3, 4 and 6 (not shown indetail) causes in some cases a slight deformation of the shearing rim141 between the place where it is gripped in the sabot 10 and the placewhere the soldered connection starts on the edge of the base surface 111of the projectile body boat-tail 110, that is, a forward bendingdeformation of the shearing rim 141 occurs. If through this theconnecting piece 14 at the periphery of the base surface 111, thereforeat the most highly stressed point of the soldered connection, as aresult of cracks in the latter, were to begin to come loose from thebase surface 111, for example, from the impact on the chamber or duringtransport, the danger would occur that, after further deformation of theshearing rim or of the connecting piece, the crack could progressradially inwards .and the projectile body 11 would then prematurelyseparate completely from the connecting piece 14. l

With the versions as in FIGURES 3 and 3a to 6 and 6a, the truncatedcone-shaped thickenings 142a, 142b or 142C and 147 now represent astrengthening compared to the disc 14a as in FIGURES 2 and 2a throughwhich, after a possible tearing-off of the soldered connection, thisadditional deformation described, and therewith the danger of a completeseparation of the projectile body 11 from the connecting piece 14, areprevented.

With the arrangement of the soldered connection between the base surface111 of a projectile body 11 and a -connecting piece 14, solder canaccumulate between the front surface of the latter and the generatedsurface of the tapered projectile boat-tail that again solidiiies,namely either in isolated places, or in the most extreme cases on thewhole circumference of the projectile boattail 110. These accumulationsof solder can impede the shearing-off of the shearing rirn 141. Toprevent this, the connecting part can be constructed as in FIGURE 5.

With this construction, interference with the shearing process by anaccumulation of solder on the outer edge of the base surface 111 of theprojectile body 11, such as is represented by ring 22 in FIGURE 5 forexample, is prevented. Compression of the surface of cut 144 of theshearing rim 141 on the rearward movement of the projectile body 11 inthe sabot 10 takes place here through the generated surface 147b of thetruncated cone 147.

Obviously the connecting pieces constructed as in F-IG- can also besupplemented with a truncated cone 147 which, as in the version as inFIGURE 5, lies in front of the plane containing the front surface of theshearing rim 141.

We claim:

1. A sabot projectile comprising a projectile body having a'base surfaceat one end, a disc-shaped connectlng piece se-cured to said base surfacehaving a rim extending circumferentially beyond said base surface, asleeve shaped sabot for receiving said projectile body formed at one endby a wall portion, a ring surface on said'wall portion defining acircular recess in said wall portion, said ring surface coaxiallyseating against said rim and defining a circular shearing edge aroundthe perlphery of said recess to shear through said connecting piece whenthe sabot projectile is discharged by the lnertia of said projectilebody causing said base surface to enter said recess.

2. A sabot projectile according to claim 1 wherein said connecting pieceis secured to said base surface by a hard solder.

3. A sabot projectile according to claim 1 wherein said connecting pieceis a disc of uniform thickness.

4. A sabot projectile according to claim 3 wherein sald connecting pieceis provided on its rear side with a tapering coaxial truncated circularcone.

5. A sabot projectile according to claim 4 wherein the depth'of saidcircular truncated cone is at least equal to the thickness of said disc.

`6. A sabot projectile according to claim 4 wherein the generating angleof said truncated cone is greater than the angle of jamming in the axialdirection of said truncated cone in relation to said recess.

7. A sabot projectile according to claim 4 in which the rear end surfaceof said truncated cone has a diameter which at most is equal to that ofthe base surface of said recess.

8. A sabot projectile according to claim 3 wherein said connecting pieceis provided on its front side with a coaxial truncated circular conetapering to the rear.

9. A sabot projectile according to claim S wherein the depth of saidcircular truncated cone is at least equal to the thickness of said disc.

10. A sabot projectile according to claim 8 wherein the generating angleof said truncated cone is greater than the angle of jamming in the axialdirection of said truncated cone in relation to said recess.

11. A sabot projectile according to claim 3 wherein the clearance of thebottom of said recess from the rear side of said connecting piece is atleast equal to the thickness of said disc.

12. A sabot projectile according to claim 1 wherein said base surface isformed as a coaxial truncated circular cone tapering to the rear.

13. A sabot projectile according to claim 1 wherein said recess is acircular cone-shaped coaxial recess tapering towards the rear whoseupper periphery forms said shearing edge.

14. A sabot projectile according to claim 13 wherein said upperperiphery has a diameter as large as the diameter of said base surface.

15. A sabot projectile according to claim 1 wherein a casing is mountedat the rear side of said connecting piece containing material for theproduction of gases.

16. A sabot projectile according to claim 15 wherein said wall portionhas a hole, open to the rear, accommodating said casing.

17. A sabot projectile according to claim 16 wherein a truncatedcone-shaped aperture is provided in said sabot communicating with saidhole.

1S. A sabot projectile comprising a projectile body having a rearsurface, a sabot in which said body rests, a connecting part forming aseparable mounting of said body in said sabot, said connecting parthaving an edge protruding beyond said body, means for fastening saidconnecting part to said rear surface, said sabot having a circularsurface, means for supporting said edge adjacent said circular surface,said sabot having a recess surrounded by said circular surface and saidrecess forming jointly with said circular surface a circular coaxialedge to form a shearing means for said connecting part.

19. A sabot projectile as set forth in claimy 18 wherein said rearsurface of said body is a coaxial circular truncated cone taperingtowards the rear and said circular surface on said sabot is a planecoaxial circular surface and said recess being formed as a coaxialtruncated circular cone tapering towards the rear with the base locatedin the plane of said circular surface, said circular truncated coneforming an edge with said circular surface the diameter of which is atleast equal to the diameter of said rear surface.

20. A sabot projectile as set forth in claim 18 wherein said means forfastening said connecting part to said rear surface is a soldered joint.

21. A sabot projectile as set forth in claim 18 wherein said connectingpart is a disc having a uniform thickness throughout said edge andwherein said connecting part is secured to said rear surface by a hardsolder.

22. A sabot projectile as set forth in claim 18 wherein said connectingpart is a disc having a circular truncated cone on one of its sidestapering towards the rear.

23. A sabot projectile as set forth in claim 22 wherein said rearsurface of said projectile body is shaped as a truncated cone and saidcircular truncated cone on said disc is at least equal to the thicknessof the peripheral edge of said disc.

24. A sabot projectile as set forth in claim 18 wherein a coaxial plugis mounted in the rear of said sabot wherein said circular surface andsaid recess is provided.

25. A sabot projectile as set forth in claim 24 wherein a casingcontaining a material for producing gases is provided in said plug.

26. A sabot projectile as set forth in claim 25 wherein said plug isprovided with a bore extending therethrough in which sai-d casing ismounted.

References Cited UNITED STATES PATENTS 388,413 8/1889 Hawley et al.102-93 X 1,328,247 8/1943 Alexander 102-93 3,044,400 7/ 1962 Detwiler102-93 FOREIGN PATENTS 496,991 10/1919 France.

SAMUEL FEINBERG, Primary Examiner.

BENJAMIN A. BORCHELT, Examiner.

R. F. STAHL, Assistant Examiner.

1. A SABOT PROJECTILE COMPRISING A PROJECTILE BODY HAVING A BASE SURFACEAT ONE END, A DISC-SHAPED CONNECTING PIECE SECURED TO SAID BASE SURFACEHAVING A RIM EXTENDING CIRCUMFERENTIALLY BEYOND SAID BASE SURFACE, ASLEEVE SHAPED SABOT FOR RECEIVING SAID PROJECTILE BODY FORMED AT ONE ENDBY A WALL PORTION, A RING SURFACE ON SAID WALL PORTION DEFINING ACIRCULAR RECESS IN SAID WALL PORTION, SAID RING SURFACE COAXIALLYSEATING AGAINST SAID RIM AND DEFINING A CIRCULAR SHEARING EDGE AROUNDTHE PERIPHERY OF SAID RECESS TO SHEAR THROUGH SAID CONNECTING PIECE WHENTHE SABOT PROJECTILE IS DISCHARGED BY THE INERTIA OF SAID PROJECTILEBODY CAUSING SAID BASE SURFACE TO ENTER SAID RECESS.